Gear vender
I wish I could FIND a GV unit. My son is looking for one as well.both for 727s
I figured with all the old 440s being pulled out of motorhomes they'd be plentiful but no.
IMO;
I think you might be better off with an A500/518 or one of the GM offerings.
The only reason I have a GVod is cuz I have a manual trans and I am
able to split gears with it.
If I was an automatic kind of guy, I would have one of the above.
Or, I would simply redesign my engine to run a regular loc-up Torqueflite.
Here are the clinchers;
If you break your GVod, it has to go back to the factory for a very expensive overhaul; cuz they will not sell you any tools.
Nor will they sell you a different adapter, without you sending them back the one you already own. The unit uses GM speed-O gears, so you may have to buy several, and/or a multiplier to run your Factory Speed-O-meter.
Whereas, you can get your A500 or 700R4 rebuilt anywhere, cuz any good trans shop will have all the tools required.
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What I mean is this; the 727 ratios are
2.45-1.45-1.00 with splits of .59/.69. For a performance streeter this is a real compromise. To be sporty, I like to gear my ride to run out of revs at the top of Second close to 60 mph. In this example; 4.56s will get you about 60*mph=5400, so that's right on.... except 65 in Drive =3690 at Zero-slip. And there-in lies the problem.
If you gear the car for 65=2700say, that requires 2700/3670 x 4.56=3.33s/ rounds to 3.23s. But 3.23s will hit 60 in Second at only 3900, and your SBM is barely awake at that rpm. So you might need a bigger engine with a smaller cam to make 3.23s work with Torqueflite.
Now if you study this out; you find that, what you really need is a specific overall Second gear ratio, that could be equal to about 6.80 This will get you 60= 5100(0% slip), say5600@10% slip, for a power peak around 5200 which is a nice friendly streetcam around 230*@.050 ..... or with Good heads maybe one size smaller.
OK, well 6.80 with a Torqueflite is; 6.80/1.45=4.69 gears; rounds down to 4.56s.
>But of all the autos that can easily be bolted to an SBM, the 700R4 has the highest Second gear at 1.63, so; 6.80/1.63=4.17 rear gear, rounds to 4.10s. Better than 4.56s for sure but still pretty far out there. And, it's about the best gearing you can get with an auto, for these parameters.
>whereas, the A500 has a pretty good Second gear at 1.54; so 6.80/1.54= 4.41 gears, rounds down to 4.30s, which will get you 60=5440 (10% slip) Not bad. Now, 5440 could be the shift rpm, and so the powerpeak could be at say 5000now, which points to a 224*
[email protected]; or with good heads, maybe a size smaller.
>And 65=2400(zero-slip) Looking good.
The starter gear would be 4.30 x 2.74=11.78 which means for a streeter, you don't need much of a stall, if any.
Lets say you installed this A500 with 4.30s.
32mph would be 1710(0-Slip) in direct/
2900 in Second at 10% slip/5170 in First@10% slip. Not the best in Second, so yur gonna need some torque, or a higher stall if you want performance. But Second
road gear is 4.30 x 1.54=6.62 so maybe it will wind up fast enough for you. (my
[email protected] Second roadgear, explodes the tires lol.)
>Ok now here is where the R700 sorta shines; Second roadgear is 4.56 x 1.63=7.41 and at 32 mph, the rpm would be
3250(10% slip). But 60=6100(10% slip) long past the powerpeak. and
65=2520(0-Slip) in overdrive.
For this reason I favor the A500. The 1-2 split is wider, but geared right, it just disappears in the starter gear.
*All calculations were done with 27" tires.
To recap, the ratios are;
2.45-1.45-1.00 for 727/904s
2.74-1.54-1.00-.69 for the A500
3.06-1.625-1.00-.70 for the 700R4
For 60=5600 in second, the Roadgears would need to be
with 1.45 second = 4.65 rounds to 4.56
with 1.54 second = 4.38 rounds to 4.30
with 1.625 second =4.15 rounds to 4.10
And so the road gears would be;
11.17-
6.61-4.56 for the regular Torqueflites, and 65=3690
11.78-
6.62-4.30-2.97 for the A500 ....................65=2400
12.55-
6.66-4.10-2.87 for the 700R4 ................. 65=2320
11.17-
6.61-4.56-3.56 for the 727/GVod ............ 65=2880
the 4L80 has tighter ratios of
2.48-1.48-1.00-.75 and splits that I really like, of
.597- .676-.75 but there is no way to get a decent overdrive, together with a nice 2nd.
Road gears would be;
11.31-
6.75-4.56-3.42 and 65=2770 with 4.56s
10.66-
6.36-4.30-3.225 and 65=2610 with 4.30s
But the splits are pretty nice.
I like 4.30s cuz it is the biggest gear to still have a 10T pinion, the ratio being 43/10=4.30
Whereas 4.56s are 41/9, 4.88s are 39/8 IIRC
sorry my post turned into a novel, again.
